NASA Ponders Death & Sex On Mars Mission

When should the plug be pulled on a critically ill astronaut who is using up precious oxygen and endangering the rest of the crew? Should NASA employ DNA testing to weed out astronauts who might get a disease on a long flight?

With NASA planning to land on Mars 30 years from now, and with the recent discovery of the most "Earth-like" planet ever seen outside the solar system, the space agency has begun to ponder some of the thorny practical and ethical questions posed by deep space exploration.